Field of the Invention
This innovation relates to spectrum management for wireless communications systems and in particular to a method and apparatus for concurrent transmit and receive functions as part of electronic countermeasures.
Related Art
When transmitting information over a wireless channel, the wireless signal is transmitted by a transmitter into free space to be received by a receiver at a remote location. As with many broadcast formats, the wireless signal may be freely received by any party with an antenna and receiver tuned to receive and process the transmitted signal. However, in many instances it is preferred or required to maintain a secure communication channel. While many systems have been developed to establish a private communication link between a wireless transmitter and receiver, many other systems have been developed to intercept and decode the information transmitted over the private communication link. This may include personal communication environments, military, or government agencies that utilize jamming signals or other means to mask or disrupt the private communication link to prevent intercept and decoding by a third party.
As a specific example, military operators and domestic first responders are constantly threatened by improvised explosive devices (IEDs), vehicle-borne improvised explosive devices (VBIEDs), radiological dispersion devices (RDDs), and other penalties. Too often, these penalties can be initiated by remote RF transmitters. Responders have used broadband jammers to flood the airways with RF energy to prevent remote triggering of these devices or have used reactive jammers that have a limited number of RF channels that they can simultaneously protect. Also, responders and operators do not always have prior knowledge of the threat spectrum and have had to presume against what specific threats to protect.
The current prior art is limited to either receiving radio frequency (RF) signals for signal intelligence (SIGINT) or transmitting RF signals as electronic countermeasures (ECM). In the area of electronic counter measure, there have been two basic prior art approaches, namely a high power, all channel jammer approach and a selective jammer approach. Both of these prior art options suffer from disadvantages. The high power, all channel jammer approach utilizes too much power because all channels are flooded with high power jammer signals. This approach also prevents friendly communications because all channels are flooded with high power jamming signals. The selective jammer approach sends out a jamming signal on certain channels, but difficulties arise in determining which channels to jam and which to leave open. Channels left unjammed created an unwanted risk for first responders or other personnel. In addition, a proficient adversary can analyze the countermeasure being deployed and can make adjustments to avoid being denied.